Vancomycin and Piperacillin-Tazobactam Dosing for a 69-Year-Old Patient Weighing 69.4 kg
For a 69-year-old patient weighing 69.4 kg, the recommended doses are: vancomycin 15-20 mg/kg (1041-1388 mg) IV every 8-12 hours with target trough levels of 15-20 μg/mL for serious infections, and piperacillin-tazobactam 3.375-4.5 g IV every 6 hours.
Vancomycin Dosing
Initial Dosing
- Calculate vancomycin dose based on actual body weight: 15-20 mg/kg every 8-12 hours 1, 2
- For this 69.4 kg patient: 1041-1388 mg per dose (round to 1000-1250 mg for practical administration) 1
- For serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, pneumonia), use the higher end of the dosing range 1
- Consider a loading dose of 25-30 mg/kg (1735-2082 mg) for critically ill patients with suspected MRSA infections 1
Monitoring
- Obtain trough vancomycin concentrations prior to the fourth or fifth dose (at steady state) 1, 2
- Target trough concentrations of 15-20 μg/mL for serious infections 1
- For less severe infections like uncomplicated skin and soft tissue infections, lower trough concentrations may be acceptable 1
- Monitor renal function regularly, especially when combined with piperacillin-tazobactam due to potential increased risk of acute kidney injury 3, 4, 5
Piperacillin-Tazobactam Dosing
Standard Dosing
- For most infections: 3.375 g IV every 6 hours 6, 7
- For nosocomial pneumonia: 4.5 g IV every 6 hours 6, 7
- Total daily dose should not exceed 18 g (16 g piperacillin component) 6, 7
Special Considerations
- For severe infections, consider the higher dose of 4.5 g every 6 hours to ensure adequate coverage 6, 7
- Extended infusion (3-4 hours) may be considered for severe infections to maintain plasma concentrations above MIC 6
Renal Function Considerations
- If creatinine clearance is >40 mL/min, no dose adjustment is needed for either medication 7
- If creatinine clearance is 20-40 mL/min, reduce piperacillin-tazobactam to 2.25 g every 6 hours 7
- If creatinine clearance is <20 mL/min, reduce piperacillin-tazobactam to 2.25 g every 8 hours 7
- Adjust vancomycin dose based on trough levels and renal function 1, 2
Combination Therapy Considerations
- Monitor renal function closely when using this combination, as several studies have reported increased risk of acute kidney injury 3, 4, 5
- Some recent evidence suggests the increased creatinine seen with this combination may represent pseudotoxicity rather than true kidney injury 8, 9
- Consider alternative combinations (e.g., vancomycin plus cefepime) if the patient has pre-existing renal impairment 5
Duration of Therapy
- Duration depends on the specific infection being treated 1
- For most serious infections, 7-14 days of therapy is recommended 1
- For complicated intra-abdominal infections, 7-10 days is typically sufficient 1
Remember to adjust doses based on clinical response, microbiological data, and monitoring parameters to optimize efficacy while minimizing toxicity.